For example, omissions and dropouts of requests which occur in system development lead to an increase in cost of modification due to a procedure turned back from a later step. Therefore, the importance of early detection of omissions and dropouts is widely known. In recent years, to detect the omissions and dropouts of requests, a human visually inspects whether or not there is a problem in documents in which requests are described while viewing inspection items that are prepared in advance. Further, in a case where there are a reflection source document and a reflection destination document such as a request for proposal (REP) and a proposal corresponding thereto or a specification and the proposal corresponding thereto, a person also visually inspects whether or not parts corresponding to individual matters described in the reflection source document exist in the reflection destination document.
However, the inspection of a large volume of documents including overlapping descriptions raises a problem of requiring much cost (personnel expenses, time, and the like). Further, there is also a problem in that the omissions, dropouts, and the like may be overlooked in manual work. Also in general documents, manual verification work is conducted for inconsistent points and ambiguous points of the document, the omissions and dropouts of the matters of a source document from another document created based on the original document, and the like. This also requires much cost and leaves the problem in that overlooking may occur in the manual work.